18. MID- TO LATE QUATERNARY STABLE
ISOTOPIC STRATIGRAPHY AND PALEOCEANOGRAPHY AT SITE 919 IN
THE IRMINGER BASIN1

Benjamin P. Flower2

ABSTRACT

Stable isotopic records based on the planktonic
foraminifer Neogloboquadrina pachyderma
(sinistrally coiling) from Holes 919A and 919B from the
western Irminger Basin (62°40´N, 37°28´W) provide
records of surface water environments of the mid- to late
Quaternary in the Irminger Sea. The 147-m sequence
clearly shows oxygen isotope Stages 1 through 20
(possibly to 25). Assignment of oxygen isotope stages is
supported by calcareous nannofossil biostratigraphy,
magnetic polarity stratigraphy, and strontium isotope
stratigraphy. Sedimentation rates average ~17.9 cm/k.y.
for the 960420 ka interval and ~13.4 cm/ k.y. for
the 4200 ka interval. Significantly, interglacial
delta18O in Stages 21 through 15 is 0.5
to 0.8 lower than in succeeding interglacials,
suggesting warmer sea surface temperatures and/or lower
salinity in this interval. The magnitude and rapidity of
these low-delta18O events suggest large
variations in salinity of the Irminger Sea during the
860600 ka interval, perhaps reflecting greater
meltwater flux derived from the Greenland Ice Sheet.